By utilizing the principle of imaging and a digital micromirror device, a projector may project a micro image onto a huge screen, and provide sufficient brightness, so as to share image information to the audience.
FIG. 1 is a schematic diagram illustrating the component configuration of a conventional projector. As shown in FIG. 1, the conventional projector 1 includes a digital micromirror device 10, a total internal reflection (TIR) prism set 11, and a reflector 12, a lens module 13, and a light guide tube 14. To define the viewing direction, the right side of FIG. 1 shows the three axes of the Cartesian coordinate system. In FIG. 1, the X-axis is the direction from the origin to the right side, the Y-axis is the direction from the origin to the lower side, and the Z-axis is the direction pointing toward the plane. In the conventional projector 1, a light passes through the lens module 13 via the light guide tube 14, and is then reflected to the TIR prism set 11 by the mirror 12; finally, the imaging light is transmitted to the lens via the digital micromirror device 10 to be projected onto the screen. However, due to physical limitations of conventional uniaxial rotating digital micromirror device 10, the uniaxial rotating DMD in the conventional projector 1 can only accept oblique incident light. Therefore, the TIR prism set 11 is inclined for an angle (e.g., 45 degrees) with respect to the digital micromirror device 10, thus limiting the volume of the conventional projector 1. To date, the size of the conventional projector 1 is too large for miniaturization of the projector, leading to lack of convenience and gradually losing competitiveness.
Therefore, it is very important to develop a projector with a smaller size.